1. Field of the Invention
The present invention relates to a molding die and a molding method, and more particularly, it relates to a molding die and a molding method employed for molding a composite item.
2. Description of the Background Art
In general, a composite item is manufactured by autoclave molding of a prepreg material of glass fiber, carbon fiber, aramid fiber or the like, or hybrid fiber of glass fiber, carbon fiber, aramid fiber or the like. In the autoclave molding, a molding die manufactured by machining a metallic material such as an aluminum material or a low-expansion metallic invar, or an epoxy resin mold or a nickel electroformed mold inversion-manufactured from a master model of synthetic wood or the like is used.
In molding, the prepreg material is set on a die-shaped surface of such a molding die in an autoclave, and the prepreg material is thereafter covered in order of a peel ply, a bleeder cloth and a vacuum bag film. A stud to which a vacuum pipe is coupled is passed through the vacuum bag film and set in contact with the outer edge of the bleeder cloth. Then, the interior of the autoclave is set to a high pressure (0.3 to 0.7 MPa), and evacuation is performed through this vacuum pipe. Thus, air around the prepreg material is discharged through the peel ply and the bleeder cloth, and the prepreg material adheres to the die surface with pressurization from the outer surface of the bleeder cloth.
Then, the temperature in the autoclave is increased to a prescribed level (at least 100° C.), and this state is held for a constant time. Thus, the prepreg material is hardened in a state deformed into a desired shape. When the hardening terminates, a composite item is manufactured by extracting the prepreg material from the autoclave and releasing the item from the molding die.
The aforementioned conventional autoclave molding is premised on the use of the high-priced autoclave, and hence the cost for the composite item increases. Further, it follows that the autoclave is occupied for a constant time including the rise and fall times of the temperature, and it cannot be said that productivity is excellent. In addition, evacuation of the prepreg material is performed in the autoclave, and hence the adhering situation of the prepreg material to the die surface cannot be sufficiently confirmed. Particularly in a large-sized composite item, it is not easy to increase adhesiveness of a central portion by evacuation with the stud, and hence there is a possibility of reducing the yield of the item.
The present invention has been proposed in order to solve the aforementioned problems, and an object thereof is to provide a molding die and a molding method improving the quality and the productivity of a composite item without employing an autoclave.